Update on Calibration of Hall Probes when EVD Style Flywheel Bearings are utilized
Usage:
CONFIDENTIAL TIBU4057-00
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TECHNICAL INFORMATION BULLETIN |
February 11, 2004 |
Uninterruptible Power Supply |
UPS 300 (CNM, CPZ) UPS 301 (CSY) UPS 600 (CTX) UPS 900 (CRY) UPS 250 (APZ, CNM, BEE) UPS 500 (CSE) UPS UTP (CPM) |
Component Code(s) 4480 |
SUBJECT: Update on Calibration of Hall Probes when EVD Style Flywheel Bearings are utilized.
REFERENCE: SEBD9328-00 UPS Flywheel Bearing Upgrade
PROBLEM: As a result of the recent flywheel bearing upgrade, the calibration process for the Hall Probe Sensors had to be enhanced. The new style EVD bearings are designed with a special elastomer type o-ring. This o-ring is between the bore of the bearing cartridges and the outer bearing race. This new EVD bearing will allow the flywheel rotor to tilt in any direction as determined by the levelness of the floor structure where the UPS is mounted. This movement of the flywheel rotor will result in the air gap between the pole ring and the flywheel rotor to change significantly. This air gap change will cause incorrect Hall Probe Sensor readings or restrict the insertion of the gauss meter probe during calibration.
SOLUTION: The flywheel rotor must be flat, prior to calibration of the Hall Probe Sensors. The recommended method to ensure that the flywheel rotor is flat is to install the flywheel shipping retainers and the rotor shims. The shipping retainers will secure the flywheel rotor in a vertical plane. The rotor shims are used to allow the flywheel rotor to rest on a surface in order to provide a known air gap on both the top and bottom of the flywheel rotor. The rotor shims will prevent the flywheel rotor from tilting. The rotor shims will also assist in preventing the Hall Effect Probes from being crushed while you are performing the calibration.
If you would like to convert your Hall Probe Sensor to the new Load Cell Sensor, a Caterpillar Retrofit Kit (207-8751) is available. This Retrofit Kit applies to UPS units (Version 2.4 or higher). The Retrofit Kit includes all applicable components and written instructions.
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